(Health.com) -- The first few months after a prostate cancer diagnosis may be an especially perilous time for men, but not because of the cancer, new research suggests.

Historically, men who get a diagnosis of prostate cancer have been nearly twice as likely to kill themselves and more likely to die of heart-related causes soon after their diagnosis compared with men in the general population, a study has found.

The increased risk of suicide and cardiovascular death "reflect only the tip of the iceberg of anxiety, mood disturbance, and perhaps other mental illness (or suffering) after a prostate cancer diagnosis," the authors write.

Fortunately, earlier diagnosis of prostate cancer, thanks to prostate-specific antigen (PSA) testing, may have slowed and even reversed these trends, according to the study, which was published in the Journal of the National Cancer Institute.

In the study, researchers at Harvard Medical School analyzed a national database of cancer statistics in which nearly 350,000 men diagnosed with prostate cancer between 1979 and 2004 were followed for a year after receiving their diagnosis. During the follow-up period, 148 of the men committed suicide and 6,845 died from cardiovascular causes, such as heart attack or stroke.

The researchers compared the suicide and cardiovascular death rates in the study-- which were very low, in absolute terms-- with those in the general male population in the United States. The suicide rate among the men with prostate cancer was 40 percent higher in the year following their diagnosis, and 90 percent higher in the first three months than it was among men the same age who didn't have cancer, according to the study.

"Suicide is a relatively rare occurrence among cancer patients, but these findings suggest the presence of significant distress," says Dr. Stephanie Misono, M.D., a resident in otolaryngology at the University of Washington. Misono led a similar study on suicide among cancer patients in 2008 but was not involved in the current research.

The cardiovascular death rate, meanwhile, was more than twice as high among the men in the first month after diagnosis than it was among cancer-free men, although it was just 9 percent higher over the course of the whole year. Among men with cancer that had spread beyond the prostate (metastatic cancer), the death rate in the first month was more than triple that in the general population.

The increase in cardiovascular deaths may be due to the psychological stress caused by the diagnosis, according to the study; stressful life events have been linked to heart attacks and other heart problems. Some prostate-cancer treatments-- such as surgery-- may also be responsible for the uptick in cardiovascular deaths, the researchers note.

However, the spike in post-diagnosis suicides was observed only in the years before1993, before the widespread use of PSA tests, which are able to detect prostate cancer early. Prostate-cancer diagnoses in the so-called PSA era may have been less traumatic, the researchers suggest, because cancers identified by PSA are more likely to be slow-growing or harmless enough that they don't require immediate treatment.

Similarly, the increase in the cardiovascular death rate in the first month after diagnosis was substantially lower during the PSA era than it was before 1993. After the first month, in fact, the death rate among prostate-cancer patients during the PSA era was lower than it was among cancer-free men, according to the study. This may be because men who undergo PSA testing tend to be more health-conscious, the researchers suggest.

The study's findings echo those of previous studies, including a study of Swedish prostate-cancer patients by the same team of researchers. "There is some controversy around it, but I think the majority of studies are starting to show that suicide may be higher in cancer patients," says Dr. Jitender Sareen, M.D., an associate professor of psychiatry at the University of Manitoba, in Winnipeg.

The study's authors say their findings underscore the importance of emotional support and counseling for people with new diagnoses of any type of cancer. Men who were single, separated, or divorced at the time of their prostate-cancer diagnosis were at greater risk of both cardiovascular risk and suicide compared with men who were married or living with a partner when they got a diagnosis, according to the study.

"There is no standardized approach to suicide prevention in cancer patients," says Misono, "but a willingness to listen and be open about the impact of a cancer diagnosis is likely to be an important element in identifying patients who are in distress and may be at increased risk."

The effectiveness of emotional and social support after a cancer diagnosis has not been tested, however. "Trying to manage the stress and having social support may reduce the risk of mortality," says Sareen, who has studied suicide risk and suicidal thoughts among cancer patients, but wasn't involved in the current study. "It makes a lot of sense, but nobody's actually done that study."

Dr. Wayne Kendal, M.D., a radiation oncologist and professor at the University of Ottawa, advises against drawing definitive conclusions from the study. The authors' explanations are "speculative," he says. "It's important to recognize that we really don't know what's happening within these data."

The researchers looked back at the events that had already happened, Kendal points out. And in retrospective studies, he says, it's harder to control for common risk factors-- such as diet-- that might contribute to both prostate cancer and heart problems.

Likewise, Misono says that clinicians and researchers may need to pay greater attention to common risk factors for prostate cancer and suicide, such as depression, pain, and decreased quality of life.

"This article is quite interesting but it should be viewed as being hypothesis-generating, not something that's showing a firm conclusion," says Kendal. "It's something that raises questions."